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  • 1
    Electronic Resource
    Electronic Resource
    Synaptic drive contributing to rhythmic activation of motoneurons in the deafferented stick insect walking system (2004)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A general feature of motor patterns for locomotion is their cyclic and alternating organization. In walking, for example, rhythmic activity in leg motoneurons innervating antagonistic muscles of a joint is primarily antiphasic within each cycle. We investigate which role central pattern generating networks play in the generation of leg motoneuron activity in the absence of sensory feedback. We elicited activity in antagonistic flexor and extensor tibiae motoneurons in the deafferented mesothoracic ganglion of the stick insect by mechanically stimulating the head or abdomen, while recording intracellularly from their neuropilar processes. In most cases, tactile stimulation induced coactivation of tibial motoneurons. However, in ≈ 25% of the trials, tibial motoneurons generated alternating cycles consisting of bursts of action potentials that were terminated by strong inhibitory synaptic inputs. Injection of depolarizing current increased the amplitude of the inhibitory phase of the oscillation, while hyperpolarizing current decreased it and revealed a tonic depolarization of the motor neurons during the bout of rhythmic motor activity. The same results were gathered from recording tibial leg motoneurons during ‘twitching’ motor activity in decerebrated animals. Our results indicate that alternating rhythmic motoneuron activity in the deafferented stick insect walking system results from phasic inhibitory drive provided by central pattern generating networks. This inhibitory input patterns the firing of the motoneurons that results from a tonic depolarizing drive. This tonic depolarizing drive was also observed in tibial motoneurons of the deafferented mesothoracic ganglion during walking movements of the intact ipsilateral front leg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2004.03312.x
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  • 2
    Electronic Resource
    Electronic Resource
    Flux Ropes Embedded In A Radial Magnetic Field: Analytic Solutions For The External Magnetic Field (2000)
    Springer
    Solar physics 197 (2000), S. 135-148 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a new exact solution of the magnetostatic equations, describing a flux rope embedded in a radial magnetic field. Its axis is perpendicular to the radial direction and parallel to the ecliptic plane and it has a radius r 0 and an arbitrary angular distance θ0 to the polar axis of the Sun. We outline the general method of how one can gain a new solution of the magnetostatic equations by rotating the vector potential of a known solution by an angle θ0 in the r−θ plane. Using the flux-rope solution, a construction procedure for an approximate solution which describes a torus around the polar axis and which is embedded in a radial magnetic field is given. The method has considerable potential as a tool for initializing numerical simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026547911807
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Endothelin-1 induces interleukin-6 release via acctivation of the transcription factor NF-κB in human vascular smooth muscle cells (2000)
    Springer
    Basic research in cardiology 95 (2000), S. 98-105 
    Details
    ISSN: 1435-1803
    Keywords: Key words Atherosclerosis – cytokines – endothelins – inflammation – free radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The potent vasoconstrictor peptide endothelin-1 (ET-1) has been implicated in the pathophysiology of atherosclerosis and ist complications. Since inflammation of the vessel wall is a hallmark of atherosclerosis, the purpose of the present study was to investigate the influence of ET-1 on cytokine production in human vascular smooth muscle cells (SMC) as a marker of inflammatory cell activation. ET-1 (100 pM – 1 μM) stimulated interleukin-6 (IL-6) secretion from human vascular SMC in a concentration-dependent manner. The ET-A-receptor antagonist BQ-123 (10 μM), but not the ET-B-receptor antagonist BQ-788, inhibited IL-6 release. ET-1 also transiently increased IL-6 mRNA compatible with regulation of IL-6 release at the pretranslational level. Electrophoretic mobility shift assays demonstrated time-and concentration-dependent activation of the proinflammatory transcription factor nuclear factor-κB (NF-κB) in ET-1-stimulated human vascular SMC. A decoy oligodeoxynucleotide bearing the NF-κB binding site inhibited ET-1-stimulated IL-6 release to a great extent suggesting that this transcription factor plays a key role for cytokine production elicited by ET-1. Moreover, the antioxidant pyrrolidine dithiocarbamate (10 μM) inhibited ET-1-induced IL-6 release indicating involvement of reactive oxygen species in ET-1 signaling. ET-1-stimulated IL-6 secretion was also suppressed by diphenylene iodonium (40 μM), an inhibitor of flavon-containing enzymes such as NADH/NADPH oxidase. The results demonstrate the ability of ET-1 to induce an inflammatory response in human vascular SMC. These observations may contribute to a better understanding of the role of ET-1 in inflammatory activation of the vessel wall during atherogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003950050170
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    Paper (German National Licenses)
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